Same as the others. I close my window at the scheduled time (or earlier). If I opened it later than planned, so be it - I just fasted a little bit longer, that’s not a bad thing.
Otherwise, you keep having to do the math, and it’d just keep sliding until it becomes stupid.
I tend to stick to the same times. If I don’t want to eat, I don’t eat and just shrink the window. But keep in mind that one of the nice things about IF is it’s flexible. If you need to change your window because of a lunch meeting, or a social event, just do it. Day to day doesn’t make any difference - what matters is consistency over a long period of time.